In general, yes: the best solution in my opinion is to upgrade to Lr5.6.
Another option though: Download the latest (free) Adobe DNG Converter, and convert your ARW files to DNG - then you can import them in Lr4.
Rob's right though, the best idea is to upgrade. DNG is nice and all, but it's probably gonna be a big time saver to eliminate the middle step. And you may be able to get better results more quickly (my Panasonic RAWs seemed to be better out of the box in LR 5 than when I used LR4 and/or DNG conversion. It may just be that the conversion improved, but it definitely meant I had to do less work on the photos. Kind of a shame to use clunky software with such a nice camera.